Under Darkness
by section42
Summary: Commander Carol Marcus has a secret. A different angle on the storyline of "Into Darkness". Carol, OCs, Klingons, other movie characters later. Updated 18 July (sorry for the delay)! Reviews and concrit welcome.
1. Prologue - In Darkness

Carol Marcus breathed out as the door of her cabin slid shut behind her.

She hadn't been aboard the _Enterprise_ for long enough to make the room feel personal, but at least it was private, and comfortable - and it had escaped any real damage in the battle against the _Vengeance._

Before she could decide whether to flop onto her bunk or drop into the armchair, she heard the chirrup of her communicator.

By the time she'd flipped open the device, she'd already worked out who was calling her.

"Yes?" she answered, irritably.

"Karol?" The Anglish was fluent, but the underlying accent was still unmistakably alien. It was a voice that nothing to do with the brightly lit white space in which she stood. "Are you alone?"

"Of course I am," she answered, frowning as the silent motes of a Klingon beam-out swirled around her. As she reappeared on a darkened transporter pad, she snapped off her communicator, clenching it like a weapon in her lowered fist, and glared angrily at Khage. "You damn well knew that already."

"_Kai_ the human," the Klingon laughed, rapping his fist on his chest in ironic salute.

She scowled at him some more, and stalked off the raised platform of the pad, conscious as usual of the cramped proportions of the attack cruiser's transporter room - two individual positions, barely enough headroom for a modestly-sized human, and a step-down area that doubled as an access space for the deflector system behind the bulkhead.

She understood the logic behind the compact design. Minimizing space and structure improved the power-to-mass ratio of ships built purely for combat. In the Klingon fleet, larger beam-outs were generally restricted to Marines, and they used the cargo transporter in the secondary hull.

For a moment, she stood face-to-face with her handler, a blonde Starfleet officer in a skimpy blue deck dress and coordinated nail polish, staring up defiantly at a cheerfully ugly brute of a Klingon squadron leader, too broad-bodied and bulky to pass for human.

She was annoyed that she hadn't been wearing something more practical. Still, at least she was wearing sensible, flat-soled boots.

"I assume you've already figured out the details," she said quickly, preempting Khage before he could turn and stride out of the transporter room. That would have forced her to hurry after him, like a pet at its owner's heels. "Though I'm pretty sure you didn't beam me over here just to say _thank you_."

Once you chose to betray your people to the Klingons, you quickly learned a whole new set of interpersonal skills. She'd almost forgotten what it felt like to be human.

"You did well," Khage remarked, with a cheerfully ugly smile.

"Thanks," she answered. She supposed it was a complement. She supposed it was true.

The _Vengeance_ was a wreck, Khan was back in his cryo-tube, and Jupiter Station was under the control of the civilian police. All the Genesis torpedoes had been destroyed, and the entire Section 31 program had been discredited.

This was more-or-less what she'd signed up for in the first place.


	2. Chapter 1 - A Fed Walks Into A Bar

_Khitomer, Klingon Space. One year earlier_.

"I'm telling you," Specialist Azetai said, with the cheerful pedantry that only a drunken science officer could manage. "It has to be some sort of cultural hangover."

"_G'day't!_" Force Leader Madsa answered, slamming a fist down on the table, spilling both their tankards. "What if they're just dumb? Do they _need_ a reason for building targets for us to shoot at?!"

Scout Captain Khage said nothing. He'd lifted his own drink from its place beside Madsa's helmet just in time, so he simply took a cool sip, allowing his second in command and his Marine officer to bicker away goodnaturedly.

It was a good day to be arguing about exactly why Federation starships had such impractically large command hulls, and a table in one of Khitomer's outdoor taverns was a good place to be doing it.

In theory, Khitomer was an ordinary frontier outpost that just happened to be demilitarized and opened to outsiders. In intent, it was a showpiece world, designed to impress diplomatic envoys and curious alien tourists. In practice, visitor numbers were low, and Khitomer was mostly used as a comfortable second residence for the Empire's own high ranks – and a pleasant stopover for Navy crews on frontier assignments.

The three senior officers of the IKV _Harrier_ were seated to one side of a curving terrace, constructed of artfully laid smooth stonework, overlooking an artificial pool large enough to land a battlecruiser on. Beyond that, a dark, eternal forest and jagged mountain peaks, clear skies. It was very much the Klingon idea of perfection.

Still on shipboard time, they were the only people drinking this early in the local day. Most of the other visitors Khage could see were Klingons, with purebred Imperial Race predominating. There were a few familiar neighbors – Orions, obviously, and Capellans and Elaasians, recognizable by their distinctive costumes – plus some less Klingon-shaped sentients who might have been _kuve_, whether their own or someone else's. It was hard to tell.

"What I want to know is why they have such big _crews_," Madsa was saying, warming to a favored theme. "No Marines, no prize crews, and their red shirt Security don't even die well."

"What I want to know is why they have such big _ships_," Azetai countered. "Using those battlecruisers – or, worse, something the size of this new _Enterprise_ – for long range exploration that could be handled by a scout with a decent science section? It's just _wasteful_."

Khage kicked them both under the table – gently – with his armoured toecaps. "Zet, Mads, _quiet_. Fed, starboard fifteen, my mark."

The girl was standing with her hands on her hips, looking around with an interesting expression, pride disguising anxiousness. She was a being who liked to be in control of things, but she felt more unsettled here than she'd anticipated, and she didn't like it.

Madsa had already shrugged and returned to her tankard, but Azetai was studying the girl with interest – admiring her trim physique with the keen expression of a scientist faced with an interesting and exotic specimen.

She had the distinctively pale complexion that was so marked among high-caste Feds, with pale blonde hair and an even lighter skin color. By Klingon standards, she was ridiculously underdressed, wearing only a short, sleeveless tunic of some flimsy, patterned stuff, which billowed a little around her torso in the breeze. It was hard to tell if the strappy leather things on her feet were meant to be shoes, or just jewelry like the bands around her wrist.

"She looks lost," Azetai said, with a mocking smile. The pretend pity in his voice made it sound like he was saying _poor kuve_.

Khlage wasn't so sure, though. The way the human was looking around reminded him of a lot of females: she was looking for a way to re-impose her control. And that meant she was looking for a pliant male.

"Go and talk to her, then," he suggested, grinning mischievously. He wasn't sure if it was his challenging expression that decided it, or the dismissive eyeroll from Madsa.

"You know? I think I will." Zet's eyes shone brightly, and he pushed back and stood up, turning towards the girl.

"_Kai_, the Scientist," Khage grinned, raising his tankard in salute. "Blue lights, Zet."

In truth, he was curious to see how the girl reacted. Azetai was tall enough, but slender by Klingon standards, with a precise, efficient manner, a refined brow ridge, and angled tips to his ears that betrayed his mixed genetic origins.

As Madsa liked to say, Science Officer Azetai's non-Klingon DNA would never let itself be mistaken for _Romulan_.

Madsa, in contrast, was purebred Imperial Race. And she was humming _Vengeance Flies At Morning_, as if to accompany Zet with a war song as he closed in on the human, but she was tapping her foot off the beat, creating a slow, moody rhythm that subverted the whole effect.

"You're ruining that song," Khage warned her.

"No, Zet is ruining the reputation of the Navy and the ship by trying to chat up humans."

Khage grinned. "I think they're actually getting on well." Zet and the human _did_ seem to be hitting it off – a lot of eye contact, swaying movements of their bodies that seemed to be part of an unconscious dance, answer and response. As he watched, one hand gesture maneuvered around the other. They were smiling as they spoke.

Madsa snorted. "I thought Feds were _kleoni_. Why would that one want to bed _him_?!"

Khage ignored the unspoken implication of _spy_. "Perhaps it's his Vulcan DNA. The Fed women have a thing for them. You wouldn't believe the stuff we had to look at in Detached Service…."

Madsa's expression was a picture of purebred disbelief. "_G'day't_, Captain. That's _worse_."

"Maybe," Khage chuckled, and gestured for to her to be silent, as Zet and the girl turned back towards the table. "Now play nice."

She obeyed, glaring slightly.

Khage watched the girl as she approached, chatting with Zet. She did a good impression of looking interested, and there was a sway to her body as she walked. _Could be a spy. Could just be female_.

"This is Carol Wallace," Zet said. "An exoscientist at Daystrom when she's not on holiday. Unclassified research into comparative transfer mechanisms, parallel to my own Accreditation work." Then he shifted into the Federation language. "Carol, Captain Khage, my ship's commander, and Force Leader Madsa, our Marine officer."

"I can tell by her helmet," the human smiled. She was probably lucky that Mads didn't understand much of Fed beyond the word _Marine_.

"Did he tell her I report to Security, too?" Madsa asked, giving the human a hostile look. She folded her arms, and glowered. It was the expression she wore when she was imagining someone in the agonizer booth.

The human lifted one of her flat-forehead eyebrows at Zet, requesting a translation.

"That's her way of saying hello," Zet replied, sounding unconvincing.

The girl's eyes showed a flicker of uncertainty, but she hid it with a bright grin. "Well, I suppose I _did_ come here to investigate the local wildlife," she said, sitting down with a shake of her head.

With that gesture, Khage noted the way she wore her hair, with an asymmetrical parting, and straight edges that framed her face before they curled up under her jawline.

"_Zan_ Karol," he nodded, figuring she must have enough _'aase_ to understand that. She did, so he glanced at Azetai, as he settled in his seat beside her. "You did tell her I'm just a _Scout_ Captain, Zet?" He'd noticed the flash of interest in the girl's expression when she heard his rank, and he had all sorts of reasons not to want her overestimating him.

She looked at Zet, chin tipped up, eyebrows lifted. Waiting for a translation.

"The Captain's pretending not to speak your language," Zet translated, with a grin. "He wants me to make clear that the military side of _Harrier_'s mission's not that important."

Khage supposed he could let that pass. Zet's science section _was_ impressive, and not just for a ship the size of _Harrier_, although the powerful sensor package wasn't exactly single use civilian equipment.

"You're from the B6 parked in orbit, right?" she asked, with another of those bright human smiles. "I saw it from the observation lounge as we came in."

"I'm impressed," he said, in Anglish, pushing a tankard over to the human. "Now we see how well you drink."

She gave him a grin. "Captain Khage. Are you _challenging_ me?"

"Of course. I'm a Klingon. Are you in?"

She raised her eyebrows again, then lifted the tankard. Her grip was probably stronger than it looked, and her gaze was steadier than her expressive body language would suggest. She had blue eyes, matching her dress and fingernail paint.

She raised the tankard in salute. "I'm in."


	3. Chapter 2 - The Morning After

Khage stood on the chalet's balcony, looking out across the terrace and the artificial pool, and lighting up his first cheroot of the morning. With a frown, he rubbed his forehead, surprised he felt so lucid.

_No hangover yet_.

He wasn't at all sure what to think about the memory of Zet carrying the Fed girl back to the chalet in his arms. She had been laughing and hugging him, kicking her bare feet playfully. They had drunk more – Madsa had produced some green poison from somewhere – and watched two old episodes of _Battlecruiser Vengeance_ back-to-back, an experience which proved increasingly anarchic as they tried to translate for the human, and re-translate for Madsa.

It ended when Zet and the girl pitched drunkenly off the couch, and Khage ordered them both to bed.

If she was a Fed spy, he mused, she was a very good faker.

Soft footsteps padded on the deck behind him, and for a moment, he thought it was Madsa returning. For such a physically imposing being, the Marine officer could move very quietly when she wanted to.

But it was the human. Barefoot. Perhaps her strappy sandals had been jewelry, after all.

"Oh," she said, stretching. "That was quite a night."

"_Zan_ Marcus," he greeted her, with a grin.

"Morning," she nodded, with a friendly smile. Then she realized what name she'd answered to. "Oh," she said, followed by something curt and dirty and annoyed.

Khage didn't even blink. "There is no Carol Wallace at the Daystrom Institute. No Carol anything."

"Carol Anything," she frowned. "Is that my name now?"

At that, he grinned. "The last _Carol Anything_ at Daystrom was a certain Carol Marcus, a daughter of one of your Thought Admirals. She _did_ study genetic mechanisms, similar to Zet as far as this one understands these things. And she's now a Lieutenant in your Starfleet's equivalent of Detached Service."

The human breathed out. "She's me, in other words."

Khage nodded. "So perhaps the one would like to explain why a Federation spy spent last night with my Executive Officer?"

"I'm not a spy," she said. "Yes, I'm Starfleet, and yes, my name is Marcus. Carol Marcus. Lieutenant-Commander, now. And yes, my father is Admiral Alexander Marcus, Starfleet Chief of Operations. But I'm a weapons designer. Not a spy." She paused, a bob in her throat. "And I want to defect."

_Weapons designer_. Khage absorbed that surprise in silence. _Defect. And she's young for the promotion, by their standards._ "I assume this isn't just to do with tensions within your house?"

She shook her head. "Not if you're asking if I'm just trying to break away from Daddy. We're arming for an aggressive war against your people, Captain, using technologies from the future. A long-range transporter to insert agents and commandos deep into Klingon space without our ships even having to enter the Neutral Zone. A new class of battleship, three times the size of the new _Enterprise_, with armament and power output to match. They've already laid the keel of the lead ship. Someone has to stop them."

"And you thought it best to deal with this by getting drunk on Khitomer?"

"I thought I could be on a shuttle out of here before you or Zet found this," the human said, reaching into her top and producing a miniature memory core. "Elements of the transwarp beaming algorithm. Partial schematics and shipyard imagery of the battleship, some details of a new torpedo design. Enough to convince you that I'm serious, but nothing to help you reverse-engineer the technology." She looked rueful for a moment. "And instructions on how to contact me again to get the next installment."

Khage gave her an ugly half-grin. "The one controls the information, to retain her usefulness. _Kai kleon_."

She shrugged. "I don't want to end up in an agonizer booth. Or a speed-learning program. You need me _inside_ Starfleet, Captain."

Khage laughed, and leveled his disruptor pistol at her.

She looked a him in shock. He decided he liked the look.

"First lesson of negotiating with Klingons," he grinned, taking the memory device from her fingers, and pocketing it. "Klingons don't negotiate. Zet and I will review your files, and decide how you can be of use to us."

Her nostrils flared. "Of _use_?!"

"The daughter of a Fed Thought Admiral would be an enviable trophy for a Scout Captain," Khage shrugged, flipping open his communicator. "Action, _Harrier_. Beam her up."

Khage thought she looked even better when her shock was combined with outrage – jaw dropped, eyes blazing at him, as the transporter beam swirled silently around her, and plucked her from the deck.

"Apenn, put her in the cell, but don't touch her, and don't let any of the Marines know she's aboard. Don't even _think_ of using the booth. I'll deal with her when I get up."

"Affirm, Captain."

Khage pocketed his communicator and turned back towards the chalet, looking at the little device she had given him. The not-yet-sober lucidity behind his brows felt like the start of something new and exciting now.

Humming to himself, he walked back inside to wake up Zet.


	4. Chapter 3 - Enemy Plans

"They still have the same _khest'n_ saucer hull," Zet observed, frowning at the schematics of the Federation warship on the screen.

"Still, at least they hollowed out the space around his actual command pod," Khage countered, tapping the image. "Looks as though they've moved the main hangars up from the engineering section's stern, as well. See these hatches underneath?"

The two of them were sitting in front of the chalet's personal communications screen, leaning forward as they inspected the files from Carol's computer core. They had deactivated the suite's monitoring circuit to provide the necessary privacy, but the managers would take no notice. They would attribute it to the usual proclivities of Khitomer tourists, and they knew that the four beings who had shared the chalet the night before had included both a drunk human girl and a Security Commander of Imperial Race.

Azetai frowned at the deckplans. "All the same, most of it's still wasted volume, without even the outsize crew compliment to justify it. They _do_ just build their ships that way for the look of the thing." Zet dropped into a fake Fed accent, far worse than the one he used when he actually spoke Anglish. "_We are the Federation. Know us by our big round command hulls._"

"Something like that." Khage shook his head. "What are his actual performance estimates like?"

"Powerful, obviously," Zet said, flipping up statistics on his hand-held screen. "Mostly just because this thing is so _khest'n_ big. It's not exactly _clever_, and it must burn through government resources even faster than it uses antimatter."

Khage glanced grudgingly at the power curves. "Even with so much hull to cover, he must have a strong deflector."

Zet nodded. "And the hull is tough, but only through overbuilding. It's a frame design – has to be, with that _khest'n_ disk-hull. Doesn't help their shield stretch, either – a close-range torpedo salvo or a Rom plasma weapon would probably drop a section of the deflector grid for half a minute, then you could beam over some Marines and take the whole thing apart from the inside."

"Or just ambush them when they're not shielded."

"That too. Crewing is minimal, and their Security is as dependent on automation as the rest of the ship. Madsa would love this thing."

"The fancy Triseklion transporter is about their only new toy," Khage agreed. "Looks like _zan_ Karol is going to learn to get used to being a trophy girlfriend." Khage paused. "What about the torpedoes, though?"

"Stupid launcher system. Didn't check the actual torps." Zet frowned, tapping the screen of his science tricorder, and then let out a low whistle, a sound that his captain recognized immediately, accompanied by glimmering of his deep-set eyes – the expression Khage thought of as embodying the deranged Vulcan scientist who had been dissected into Azetai's DNA.

"In '_aase_, Specialist?" he asked.

"Try Anglish," Zet said, tapping his screen again. An image flipped to the front, showing a pretty high-caste human in the blue deck dress and black jackboots of a Starfleet science officer.

"Carol Marcus," Khage said, one end of his brow-ridge lifting. She suited the Fed uniform, he decided.

"Hush and listen?" Zet suggested. "This is _big_. No wonder she was scared."

Something in Azetai's tone was different. Khage leaned forward, attentively. "Action, Specialist Azetai."

Zet just clicked his screen.

"Project Genesis," Carol Marcus began. "A proposal for Section 31."


End file.
